The underperformance of the growth enterprise market in Hong Kong

This paper examines the stock return performance of the IPO stocks which are listed on the Growth Enterprise Market (GEM) in Hong Kong. By using several benchmarks, over 3 years, this paper finds that the results produced are sensitive to the benchmark employed. The two factors causing the underperformance of GEM stocks are the `technology boom and `IPO effects. This suggests that appropriate benchmarks are very important for assessing the performance of newly issued stocks. The results of the cross-sectional analyses suggest that the Hong Kong GEM is a unique market. Since at least 70 percent of the IPO stocks listed on theGEMare technology stocks, the `technology factor outweighs the various hypotheses advocated by previous researchers to explain the poor performance of newly listed stocks

Spreading-Resistance Temperature Sensor on SOI

A Spreading-Resistance Temperature (SRT) sensor is fabricated on silicon-on-insulator (SOI) wafer and achieves characteristics comparable with similar SRT sensor on silicon wafer. This sensor structure can be potentially used in integrated sensors operating at temperatures up to 350 °C.published_or_final_versio

Effects of wet N 2O oxidation on interface properties of 6H-SiC MOS capacitors

Oxynitrides were grown on n- and p-type 6H-SiC by wet N 2O oxidation (bubbling N 2O gas through deionized water at 95°C) or dry N 2O oxidation followed by wet N 2O oxidation. Their oxide/SiC interfaces were investigated for fresh and stressed devices. It was found that both processes improve p-SiC/oxide but deteriorate n-SiC/oxide interface properties when compared to dry N 2O oxidation alone. The involved mechanism could be enhanced removal of unwanted carbon compounds near the interface due to the wet ambient, and hence a reduction of donor-like interface states for the p-type devices. As for the n-type devices, incorporation of hydrogen-related species near the interface under the wet ambient increase acceptor-like interface states. In summary, the wet N 2O oxidation can be used for providing comparable reliability for n- and p-SiC MOS devices, and especially obtaining high-quality oxide-SiC interface in p-type MOS devices.published_or_final_versio

Spreading-resistance temperature sensor on silicon-on-insulator

A spreading-resistance temperature (SRT) sensor is fabricated on silicon-on-insulator (SOI) substrate and achieves promising characteristics as compared with similar SRT sensor on bulk silicon wafer. Moreover, experimental results show that the maximum operating temperature of thin-film (1.2 μm) SOI SRT sensor can reach 450 °C, much higher than 350 °C of thick-film (10 μm) SOI SRT sensor under the same current level. With complete oxide isolation, this sensor structure can be potentially used in low-power integrated sensors operating at temperatures as high as 450 °C.published_or_final_versio

Effects of nitridation and annealing on interface properties of thermally oxidized SiO2/SiC metal–oxide–semiconductor system

The effects of N2O nitridation and subsequent annealing in different conditions on thermally oxidized n-type 6H–silicon carbide (SiC) metal–oxide–semiconductor (MOS) interface properties were investigated. Influence of high-field stress on the MOS system was also studied. The nitrided device annealed in dry or wet O2 is found to have lower interface-state density compared to the device annealed in N2 because the reoxidation can reduce nitridation-induced interface damage. Furthermore, significantly less shift of flatband voltage during high-field stress for all nitrided devices indicates much better oxide reliability by replacing strained Si–O bonds with stronger Si–N bonds during nitridation. This is further supported by the fact that annealing of the nitrided device in dry or wet oxygen slightly reduces the robustness of the oxide. In summary, the O2-annealing conditions have to be optimized to deliver a proper tradoff between interface quality and reliability. © 2000 American Institute of Physics.published_or_final_versio

Validation of the Abbreviated Mental Test (Hong Kong version) in the elderly medical patient

The Abbreviated Mental Test is a useful screening test for abnormal cognitive function in the elderly patient. It is widely used in UK geriatrics practice. A modified local version of the Abbreviated Mental Test is also commonly used in Hong Kong. In the present study, the local version of the 10-question Abbreviated Mental Test was validated against clinical diagnoses of normal/abnormal cognitive function (by DSM III R criteria). Sixty-nine patients (aged 65 years and older) referred to the Acute Geriatric Assessment Team at the Queen Mary Hospital were assessed. Nine patients (13%) were excluded because of language barrier, deafness, dysphasia and/or severe dysarthria. Sixty patients completed the test and the clinical assessment. An incorrect answer in each of the test items was found to be significantly associated with abnormal cognitive function (P<0.005). For the Abbreviated Mental Test score, the best cut-off point was found to be six (below six was considered abnormal); this yielded a sensitivity of 96% and a specificity of 94%.published_or_final_versio

Fabrication and electrical characterization of MONOS memory with novel high-κ gate stack

A novel high-κ gate stack structure with HfON/SiO 2 as dual tunneling layer (DTL), AIN as charge storage layer (CSL) and HfAIO as blocking layer (BL) is proposed to prepare the charge-trapping type of MONOS non-volatile memory device by employing in-situ sputtering method. The memory window, program/erase and retention properties are investigated and compared with similar gate stack structure with Si 3N 4/SiO 2 as DTL, HfO 2 as CSL and Al 2O 3 as BL. Results show a large memory window of 3.55 V at PIE voltage of +8 V/-I5 V, high program/erase speed and good retention characteristic can be achieved using the novel Au/ HfAIO/AIN/(HfON/SiO 2)/Si gate stack structure. The main mechanisms lie in the enhanced electron injection through the high-κ HfON/SiO 2 DTL, high trapping efficiency of the high-κ AIN material and effective blocking role of the high-κ HfAIO BL. ©2009 IEEE.published_or_final_versionThe IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC) 2009, Xi'an, China, 25-27 December 2009. In Proceedings of EDSSC, 2009, p. 521-52

Improved interface properties of p-type 6H–SiC/SiO2 system by NH3 pretreatment

Effects of preoxidation NH3 treatment on p-type 6H–SiC/SiO2 interface properties were investigated as compared to conventional thermally oxidized devices. It was found that NH3 treatment before oxidation can reduce the SiC/SiO2 interface states and fixed oxide charge. Furthermore, less shift of flatband voltage, and smaller increases of effective oxide charge and interface states during high-field stress were observed for the NH3 pretreated devices. © 2000 American Institute of Physics.published_or_final_versio

Improved hydrogen-sensitive properties of MISiC Schottky sensor with thin NO-grown oxynitride as gate insulator

Thin oxynitride grown in NO at low temperature was successfully used as gate insulator for fabricating MISiC Schottky hydrogen sensors. Response properties of the sensors were compared with other MISiC Schottky sensors with thicker or no oxynitride. It was found that the thin oxynitride played an important role in increasing device sensitivity and stability. Even at a low H 2 concentration, e.g., 100-ppm H 2 in N 2, a significant response was observed, indicating a promising application for detecting hydrogen leakage. Moreover, a rapid and stable dynamic response on the introduction and removal of H 2/N 2 mixed gas was realized for the sensor. Improved interface properties and larger barrier height associated with the thin oxynitride are responsible for the excellent response characteristics. As a result, NO oxidation could be a superior process for preparing highly sensitive and highly reliable MISiC Schottky hydrogen sensors.published_or_final_versio

Sensing characteristics of a novel NH 3-nitrided schottky-diode hydrogen sensor

A novel NHi-nitrided Schottky-diode hydrogen sensor has been successfully fabricated Measurements have been performed to investigate the sensitivity, stability and response speed of the sensor at different temperatures and hydrogen concentrations. It can respond to hydrogen variation very quickly and can give significant response ewn at low hydrogen concentration. The studied device exhibits high sensitivity of 350 % at 300 °C when 800 ppm IJ in N2 gas is introduced. The sensitivity is 15 times greater than that of the Pt-SiC sensor. The excellent hydrogen-sensing characteristics of this novel sensor make it very suitable for detecting hydrogen leakage in high-temperature environment. The effects of hydrogen adsorption on the barrier height and hydrogen reaction kinetics are also investigated. ©2004 IEEE.published_or_final_versio